Index: ELF/Symbols.cpp
===================================================================
--- ELF/Symbols.cpp
+++ ELF/Symbols.cpp
@@ -91,10 +91,15 @@
     uint64_t VA = IS->getVA(Offset);
 
     if (D.isTls() && !Config->Relocatable) {
-      if (!Out::TlsPhdr)
+      // Use the address of the TLS segment's first section rather than the
+      // segment's address, because segment addresses aren't initialized until
+      // after sections are finalized. (e.g. Measuring the size of .rela.dyn
+      // for Android relocation packing requires knowing TLS symbol addresses
+      // during section finalization.)
+      if (!Out::TlsPhdr || !Out::TlsPhdr->FirstSec)
         fatal(toString(D.File) +
               " has an STT_TLS symbol but doesn't have an SHF_TLS section");
-      return VA - Out::TlsPhdr->p_vaddr;
+      return VA - Out::TlsPhdr->FirstSec->Addr;
     }
     return VA;
   }
Index: ELF/Writer.cpp
===================================================================
--- ELF/Writer.cpp
+++ ELF/Writer.cpp
@@ -1656,6 +1656,12 @@
     Phdrs = Script->hasPhdrsCommands() ? Script->createPhdrs() : createPhdrs();
     addPtArmExid(Phdrs);
     Out::ProgramHeaders->Size = sizeof(Elf_Phdr) * Phdrs.size();
+
+    // Find the TLS segment. This happens before the section layout loop so that
+    // Android relocation packing can look up TLS symbol addresses.
+    for (PhdrEntry *P : Phdrs)
+      if (P->p_type == PT_TLS)
+        Out::TlsPhdr = P;
   }
 
   // Some symbols are defined in term of program headers. Now that we
@@ -2093,13 +2099,11 @@
       P->p_memsz = alignTo(P->p_memsz, Target->PageSize);
     }
 
-    // The TLS pointer goes after PT_TLS. At least glibc will align it,
-    // so round up the size to make sure the offsets are correct.
-    if (P->p_type == PT_TLS) {
-      Out::TlsPhdr = P;
-      if (P->p_memsz)
-        P->p_memsz = alignTo(P->p_memsz, P->p_align);
-    }
+    // The TLS pointer goes after PT_TLS for variant 2 targets. At least glibc
+    // will align it, so round up the size to make sure the offsets are
+    // correct.
+    if (P->p_type == PT_TLS && P->p_memsz)
+      P->p_memsz = alignTo(P->p_memsz, P->p_align);
   }
 }
 
Index: test/ELF/pack-dyn-relocs-tls-aarch64.s
===================================================================
--- /dev/null
+++ test/ELF/pack-dyn-relocs-tls-aarch64.s
@@ -0,0 +1,34 @@
+// REQUIRES: aarch64
+
+// RUN: llvm-mc -filetype=obj -triple=aarch64-unknown-linux %s -o %t.o
+// RUN: ld.lld -shared --pack-dyn-relocs=android %t.o -o %t.so
+// RUN: llvm-readobj -relocations %t.so | FileCheck %s
+
+// Bug 37841: Symbol::getVA must work on TLS symbols during the layout loop in
+// finalizeSections.
+
+    .global foo
+foo:
+    adrp    x0, :tlsdesc:tlsvar1
+    ldr     x1, [x0, :tlsdesc_lo12:tlsvar1]
+    add     x0, x0, :tlsdesc_lo12:tlsvar1
+    .tlsdesccall tlsvar1
+
+// Also test an atypical IE access from a shared object to a local TLS symbol.
+
+    .global bar
+bar:
+    adrp    x0, :gottprel:tlsvar2
+    ldr     x0, [x0, #:gottprel_lo12:tlsvar2]
+
+    .section    .tdata,"awT",@progbits
+    .space  0x1234
+tlsvar1:
+    .word   42
+tlsvar2:
+    .word   17
+
+// CHECK:          Section ({{.+}}) .rela.dyn {
+// CHECK-NEXT:     R_AARCH64_TLSDESC - 0x1234
+// CHECK-NEXT:     R_AARCH64_TLS_TPREL64 - 0x1238
+// CHECK-NEXT:     }
Index: test/ELF/pack-dyn-relocs-tls-x86-64.s
===================================================================
--- /dev/null
+++ test/ELF/pack-dyn-relocs-tls-x86-64.s
@@ -0,0 +1,23 @@
+// REQUIRES: x86
+
+// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
+// RUN: ld.lld -shared --pack-dyn-relocs=android %t.o -o %t.so
+// RUN: llvm-readobj -relocations %t.so | FileCheck %s
+
+// Bug 37841: Symbol::getVA must work on TLS symbols during the layout loop in
+// finalizeSections. This test uses an atypical IE access in a shared object to
+// access a local TLS symbol, because a more typical access would avoid the
+// bug.
+
+    .globl  foo
+foo:
+    movq    tlsvar@GOTTPOFF(%rip), %rcx
+
+    .section    .tdata,"awT",@progbits
+    .space 0x1234
+tlsvar:
+    .word   42
+
+// CHECK:          Section ({{.+}}) .rela.dyn {
+// CHECK-NEXT:     R_X86_64_TPOFF64 - 0x1234
+// CHECK-NEXT:     }